A flat-panel CRT display basically consists of an electron-emitting device and a light-emitting device that operate at low internal pressure. The electron-emitting device, commonly referred to as a cathode, contains electron-emissive elements that emit electrons over a wide area. The emitted electrons are directed towards light-emissive elements distributed over a corresponding area in the light-emitting device. Upon being struck by the electrons, the light-emissive elements emit light that produces an image on the viewing surface of the display.
When the electron-emitting device operates according to field-emission principles, electrically resistive material is commonly placed in series with the electron-emissive elements to control the magnitude of current flow through the electron-emissive elements. FIG. 1 illustrates a conventional field-emission device, as described in U.S. Pat. No. 5,564,959, that so utilizes resistive material. In the field emitter of FIG. 1, electrically resistive layer 10 overlies emitter electrodes 12 provided on baseplate 14. Control (or gate) electrodes 16, one of which is depicted in FIG. 1, are situated on dielectric layer 18 and cross over emitter electrodes 12. Conical electron-emissive elements 20 are situated on emitter resistive layer 10 in openings 22 through dielectric layer 18 and are exposed through corresponding openings 24 in control electrodes 16.
Resistive layer 10 is typically a blanket resistor. That is, resistor 10 extends in a continuous manner over the emitter electrodes 12 and the intervening portions of baseplate 14. Consequently, each electron-emissive element 20 is electrically coupled through resistive layer 10 to each other element 20.
The resistance of layer 10 is usually sufficiently high that the intercoupling of electron-emissive elements 20 through layer 10 has little effect on the display operation. In fact, layer 10 is normally of such high resistance that layer 10 effectively electrically isolates each element 20 from each other element 20. Nonetheless, some undesirable leakage current flows between elements 20 due to the intercoupling provided by resistive layer 10.
It is desirable to have a resistive layer that provides resistance at selected areas along baseplate 14 but does not itself electrically interconnect these areas. In this regard, electron-emissive elements 20 at each location where one control electrode 16 crosses over one emitter electrode 14 operate as a unit and need not be resistively separate. It is also desirable to configure the resistive layer in such a way that underlying emitter electrodes be externally electrically accessible along their upper surfaces without the necessity of performing a separate etching operation to cut openings through the resistive layer. Furthermore, it is preferable to provide a suitable pattern in the resistive layer without employing any additional masking steps beyond those used for patterning other components in the field emitter.